Panasonic VF2 WhisperFit ventilation fans are not only as energy efficient as conventional Panasonic Ceiling fans, but they are compatible with either 3 or 4 inch duct and are only 5.5 inches deep.
Note that they are not quite as quiet as their larger Panasonic counterparts,
but nearly so, As with other Panasonic fans these fans are rated for continuous
operation, include a built-in backdraft damper, thermal fuse protection, and
rust-proof paint on a galvanized steel body. They require a 10 3/8" mounting
opening and have a grill that is 13 inches square. The grill trim is white.
Model # Specs (FV-11VF2), 3" duct:
90 cfm, 1.5 sones, 34 watts: Mounts 10 7/8 sq.
These fans will fit either 4" or 3" ducting - A adapter is included with each fan for 3" ducts.